Martin- Your dismissal of multiple expert studies which find no evidence of extraterrestrial impacts at the YD demonstrates your desire for there to have been an impact, regardless of what the data shows. I know Firestone, and I know Claeys. There is absolutely no question that Claeys is the ET impact expert, the stratigraphy expert, and the trace-element geochemistry expert (especially wrt: platinum-group elements). In contrast, Firestone was dabbling in a subject far, far removed from anything he had done before. You may want to push the impact scenario to sell something, but do not take a swipe at the science in order to do so. I spent over a decde working in the Alvarez/Asaro labs at UC Berkeley learning how to do parts per trillion measurements on GISP2 ice cores and deep-sea sediments spanning the last glacial termination, and found no appreciable change in cosmic Ir at that time interval. My work preceded Firestone’s by a good six years, and was published in Lawrence Berkeley National Laboratory Reports (negative results oftentimes are NOT put through peer-review processes in order to save trees and to respect peer referee’s time. That doesn’t mean the science is bad, it just means there wasn’t anything to report.)
Daniel Karner, Ph.D.
Professor of Geology (retired)
Sonoma State University